Television modulation system and apparatus



W. SOLLER March 12, 194.0.

TELEVISION MODULATION SYSTEM AND APPARATUS s Sheets-She et 1 Filed 001;.4, 1937 v INVENTOR.

ATTORNEY I w grw 6276624 FFif r Lift;

March 12, 1940. w. SOLLER TELEVISION MODULATION SYSTEM AND APPARATUSFiled Oct. 4, 1937 3 Sheets-Sheet 2 a INVENTOR. MM 60mm,

ATTORNEY W. SOLl-ER March 12, 1940.

TELEVISION MODULATION SYSTEM AND APPARATUS s Sheets-Sheet s Filed Oct.

INVENTOR.

gl f/tem 0506600 I ATTORNEY Patented Mar. 12, 1940 lTENT OFFICETELEVISION MODULATION SYSTEM AND APPARATUS Walter Soller, Cincinnati,Ohio, assignor of onehalf to William H. Woodin, Jr., Tucson, Ariz.

Application October 4, 1937, Serial No. 167,281 11 Claims. (01. 178-711)My invention relates broadly to television'and more particularly to animproved modulation system and apparatus especially adaptable thereto.

The system and apparatus hereinafter described are improvements intelevision systems of the type disclosed in my copending applicationsSerial Number 733,300, filed June 30, 1934, for Television system, andSerial Number 4,393, filed January 31, 1935, for Television system, andemploys a plurality of low frequency carrier currents to besimultaneously modulated by light intensities in a correspondingplurality of lines in the object televised.

One of the objects of my invention is to provide a dual photoelectricscanning system simultaneously operable to translate light intensityfrom the same portion of an object into electric signalling energy.

Another object of my invention is to provide a push-pull type of.modulation system in which light from a single point in an object iseffective on dual photoelectric means connected with a carrier currenttransmission system. A further object of my invention is to provide asingle electron tube structure enclosing dual photoelectric means in amodulation system operative to produce a push-pull modulated wave.

Still another object of my invention is to provide a single electrontube device enclosing dual photoelectric means in a scanning systemadapted to maintain the device at all times normal to the light raysreceived from the object scanned.

A still further object of my invention is to provide a pair of singlephotoelectric devices arranged for movement in synchronism with respectto dual images of an object scanned in order to produce separate signalcurrents for push-pull modulation of a carrier current.

Still another object of my invention is to provide a system forsimultaneously modulating and combining a plurality of low frequencycarrier currents, the modulations being effected in pushpull manner andin accordance with light intensity on adjacent sections of a linearportion of an object to be televised.

Other and further objects of my invention will be apparent in the systemand apparatus hereinafter described with reference to the accompanyingdrawings, in which:

Figure l is a side ,elevational view, partly in section, of one form ofapparatus, of my invention adapted to the modulation system ofmyinvention; Fig. 2 is a plan view, partly in section of the apparatusof Fig. 1; Fig. 3 is an enlarged detail view through the dualphotoelectric device in the form of my invention shown in Figs. 1 and 2,and illustrates the base mounting therefor; Fig. 4 is a schematicdiagram of the connections in the push-pull modulation system of myinvention;

view thereof with parts in elevation taken substantially on line 99 inFig. '10, Fig. 10 a horizontal sectional view thereof on line Ill-I0 inFig.

9, Fig. 11 a cross-sectional view thereof on' line l l--! I in Fig. 9,and Fig. 12 a detail sectional view on line l2-l2 in Fig. 9; and Fig. 13is a diagrammatic showing of an arrangement for scanning a moving filmby means of the essential elements of the embodiment shown in Figs.9-12.

The apparatus herein described may be employed'in combination with anytype of multiple alternator generating a sufficient plurality of carriercurrents for the several photoelectric units employed simultaneously. Analternator such as disclosed in my copending application, Serial Number733,300, may be employed and connected as shown in Fig. 4, as willhereinafter be more fully defined.

In order to make use of the push-pull modulation system of my invention,however, it is not necessary that a plurality of photoelectric units beemployed, and thesystem employing only one dual unit may be simplyconsidered by regarding only the first dual arrangement shown in Fig. 4.The structure disclosed for scanning in one dimension would have to bereplaced by twodimen'sional scanning means if only one dual unit isemployed. The same benefits attending pushpull operation, however, willbe obtained by using the system of my invention with two-dimensionalscanning systems. i

Referring to the drawings in more detail I have shown inFig. 1 a cameracasing I having an adjustable lens system 2 mounted in one side thereofand adapted to focus an image of the object to be televised in a planealong which a photoelectric device 3 is movable for scanning the image.The photoelectric device 3 contains a dual multiple cell arrangement inthe form shown more clearly in Fig. 3, and consisting of two columns ofsuperimposed, separately insulated, photosensitive elements 4 and 4',separately connected through the wall of the device by conductors 5.Associated with all of the elements 4, 4', is a common anode structure8, comprising a pair of strip members mounted parallel in the same planeand closely spaced so as to define a narrow slit constituting a scanningaperture. Referring more particularly to Fig, 3, it will be seen thatthe photosensitive elements 4, 4', are triangular in shape and incombination present the apex of a triangle normal to the scanning slitso that light entering normal to the plane of the anodes 6 and passingtherebetween will fall equally on the two sets of photosensitiveelements 4, 4'. A covering I i is provided on the exterior of the device3 to exclude light other than that passing between the anode members 6,through the scanning aperture. The tube 3 is described more fully in mycopending application Serial No. 167,282, filed October 4, 1937,'forPhotoelectric tube.

The photoelectric device 3 is mounted on a base 1 which is pivotallymounted in a carriage 8. The carriage 8- is mounted on rollers andarranged to oscillate within the casing I, being ac tuated by anysuitable reciprocatory drive mechanism from a synchronous motor 9. AScotch yoke mechanism, comprising a crank member It engaging a slot iiin the carriage 8, is shown in Figs. 1 and 2 and produces simpleharmonic motion in the carriage 8 for constant rotation of the motordriven crank lfi. Any other form of mechanism, such as one to producelinear movement in the carriage 8, may be conveniently substituted forthe Scotch yoke type shown. Cam

or electromagnetic means may be found useful in this connection. Acounter-weight for the crank ii) is shown at 14 in the drawings.

In order to maintain the photoelectric device 3 at all times normal tothe light rays forming the image, so that light may fall equally on thephotosensitive elements 4, l, the base I is mounted in bearings l5 inthe carriage 8, and is biased by mean of a spiral spring l6, securedbetween the carriage 8 and the base i, to stand normally with the planeof the anode 6 parallel to the plane of the image and slightly forwardthereof, as shown more clearly in Fig. 3 where the plane of the imagepasses through the center of the pivotal mounting of base I. Thisposition is shown in full lines in Fig. 2.

The carriage 8 is adapted to reciprocate between two limiting positionsshown in Fig. 2 in dotted lines. Forward of the carriage 8 I provide anupstanding wall member I! having a concave cam edge l8 formed on therearwardly projecting head portion thereof. The base 1 carries a roller!9 on the forward portion thereof adapted to ride on the cam edge l8.Thus, as the carriage 8 travels towards eitherof the limiting positionsthe base I and the photoelectric device 3 are pivoted in the plane ofthe image by the action of the cam edge IS on the base 1 through theroller l9 and against the tension of the spiral spring 16. As thecarriage returns to central position from either limiting position thespring it maintains the roller l9 in contact with the cam edge 18 so asto preserve the normal relation of the scanning slit and the incidentlight rays. It

. will be understood-therefore that the photosensi- Referring now to:Fig. 4, the system of my invention comprises a series of alternatingcurrent generators producing carrier currents of different frequenciesand connected separately with pairs of photosensitive units 51, 4' inthe photoelectric device 3. The alternator systemshown is of theinductor type and includes field coils 26, 20a, etc., energized from adirect current source at 2!, and. inductor coils 23 and 23', and 23a and23a, etc., coupled through a varying magnetic field produced in a corestructure, 24, 24a, etc., of varying reluctance. One terminal each ofcoils 23 and 23, 23a and 23a, etc., is connected respectively tophotosensitive elements 4 and 4'; the other terminal of each beingconnected respectively to resistance elements 25 and 26, in common, theresistance elements being connected together and through a source ofpotential 27 to the anode structure 6. Thus resistance element 25carries the currents of coils 23, 23a, etc., as modulated respectivelyby the action of photosensitive elements 6, da, etc., and resistanceelement 26 carries the currents of coils 23, 23a, etc., as modulatedrespectively by the action of photosensitive elements 4', 4a, etc. Thepotential of source 2'! is such as to provide operable positivepotential on the anode structure 6. The instantaneous potentials incoils 23 and 23 are indicated, under which photosensitive element 4' isoperative to modulate the carrier current in resistance 26 due to coil23 in negative relation and the photosensitive element 2 is operative tomodulate the carrier current in resistance 25 due to coil 23 in positiverelation; the condition upon change of polarity in both coils. 23 and23' is such as to reverse the sense of the modulation in resistance 25and 2E. The modulated currents in resistances 25 and 28 flow in the samedirection with respect to the source 21 and the potentials supplied tothe output terminals, connected as shown, are in push-pull relation withrespect to the neutral terminal 28 connected at the juncture ofresistances 25 and 28 with source 21. The output of the modulator systemis amplified and transmitted by any suitable arrangement to receivingapparatus of cooperative type.

Figs. 5, 6 and 7 show a modified form .of cam arrangement suitable foroperation in the structure shown in Figs. 1-3. The upper edge of theupstanding Wall member I? is formed with an overhanging lip portion i8convex in form and adapted to guide a roller pilot member 30 mounted ina modified base 1' having a slot for accommodating the shank portion 30of the pilot member, which is slidable with respect to the base Theshaft 3!, pivotally mounting the base 7' i. in carriage 8, has a portionthereof, extending through the slot in base i, of rectangular crosssection and the shank portion 38' of pilot member 39 has a slot engagingthe rectangular portion of shaft 3| so as to control the pivoting of thebase i and photoelectric device 3 in accordance with the movement ofpilot member 30 on the convex runner id, as shown more clearly in Fig. 5wherein the limiting positions of the car riage t are shown in dottedlines.

Fig. 8 shows schematically an arrangement for transmitting from filmrecords of light intensity, the arrangement employing a stationaryphotoelectric device 3 of the type described and a light source 32, thefilm 34 passing between the source and the device 3 at constant speed. Alens systern 35, 35a is provided to diverge the light rays passingthrough the film, which is usually of narrow width, to embracesubstantially the entire I scanned by each device.

photosensitive assembly 4, 4', in the tube 3. The film record is thussimultaneously scanned in one direction by the series of photosensitiveelements in the assembly 4, l, and in the other direction by theconstant movement of the film 32, the device 3 being disposed parallelto the width of the film. Intermittently moved film may be scanned inthe usual manner, the photoelectric device 3 being moved across theimage of each frame, and preferably in synchronism with the movement ofthe film.

Figs. 9-12 show a modified structure of photoelectric device and anarrangement for employing the device in the push-pull modulation systemof my invention. The device 36 contains a single series ofphotosensitive elements 31 as can be seen i in Fig. .10, and is of atype described in my copending application Serial .No. 167,282, filedOctober 4, 1937, for'Photoelectric tube. A similar anode structure 38 isprovided and likewise a covering 39 to exclude light except as admittedthrough the anode structure 38. Two such photoelectric devices, 36 and38', are required for push-pull modulation and the object must be Thearrangement shown in Figs. 9-12 comprises a casing l in which is mountedan adjustable lens system 2' having a lock screw 40, as shown in Fig.11. At the rear of the casing is mounted a dual mirror arrangement M insuch a manner as will reflect an image of the object focused at eitherside of the mirror arrangement, in the planes indicated on the drawing,Fig. 10. A prism .or other suitable refleeting means may be substitutedfor the mirror arrangement shown.

Means similar to that employed in the arrangement shown in Figs. 1 and 2is provided for moving the devices 36 and 36in scanning the image of theobject to be televised. This means includes a motor 9 connected with acrank member l0 and with a second crank member l0 opposite thereto. Amodified form of carriage is provided at 42 and 42' adapted to operateon rails 43 and 43 mounted within the casing i. The carriage 42 and 42'are provided with slots [2 and I2 engaging the crank members l0 and I0.It will be understood that the images formed in the image planes are inreverse relation, that is, a point in the object appearing at A in theone image will appear at A in the opposite image as indicated in Fig.10. The photoelectric devices therefore will be moved in reverserelation which is conveniently accomplished by displacement of the-crankmembers, ill and i0, 180 with respect to the driving shaft of motor 9,as shown in Fig. 9. Counterweights l4 and M are provided as in thestructure of Figs. 1 and 2.

The carriage 42 is provided in its upper portion with an adjustablemember 45 constituting a'base for mounting the photoelectric device 36.A bolt and wing nut arrangement is provided at 46 to maintain the basein adjusted position. A similar arrangement of parts is provided withrespect to carriage 42' and photoelectric device 36', the purpose ofthis arrangement being to provide separate adjustments of the positionsof the two devices 36 and 36' with respect to the focusing means 2' andthe image planes defined therefrom. Once adjusted for any particularphotoelectric device the adjustment need not be disturbed and subsequentadjustments of the lens system 2' for various objects will equallypertain to the separate photoelectric devices.

Fig. 13 illustrates schematically an arrangement for transmitting fromfilm records of light intensity employing the form of apparatus shown inFigs. 9-12. As set forth in connection with Fig. 8 the photoelectricdevices are stationary, and the film 34 is moved in a direction withrespect to the photoelectric devices such that the width of the film isscanned by the series of photosensitive elements in the devices and thelength by the movement thereof in the determined direction. A source oflight 32 and lens system 35 and 35a are employed similarly to thearrangement shown in Fig. 8. Intermittently moved film may be scanned inthe usual manner, the photoelectric devices being moved across theimages of each frame, and preferably in synchronism with the shifting ofthe film.

The push-pull modulation system of my invention is adaptable to otherscanning systems than those of the type described. Where, for example, asingle pair of light sensitive elements are employed, the pair is movedas a single unit in a two-dimensional scanning arrangement, bothelements of the pair receiving light simultaneously from the same pointin the object. In an electron beam scanning system of the type disclosedin my copending application Serial Numb er 222,897, filed Aug. 3, 1938,for Television system, or in an electron ray two-dimensional scan ningsystem, both of which operate to discharge elementary condensers chargedby the photoelectrio action of one electrode thereof, a pair of elecl1tron scanning means focused on the one elementary condensersimultaneously and moved in synchronism across the several elementarycondensers is required, providing dualsignals for the push-pullmodulation of a carrier in accordance with the system of my invention.In such systems, a second cathode source of electrons mounted foremitting electrons to be formed and deflected by the usual meanstogether with the usual electron stream is all the additional structurenecessary in order to employ the push-pull modulation system of myinvention.

Thus, while I have shown my invention in certain preferred embodiments Iintend no limitations thereby upon my invention, and modifications maybe made therein within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. In a television system, a push-pull modulation circuit comprisingphotoelectric separate sources of the same television signal energy, andmeans connected separately in circuit with said photoelectric sourcesfor supplying a carrier current in opposite phase to each of saidsources for modulation by the energy from said sources in push-pullrelation.

2. In a television system, a push-pull modulation circuit comprisingseparate photoelectric elements each subject to light rays of the sameintensities, and means connected separately in circuit with saidphotoelectric elements for supplying a carrier current in push-pullrelation to said photoelectric elements for modulation thereby.

3. In a television system, a push-pull modulation circuit comprising aplurality of pairs of separate photoelectric sources of the sametelevision signal energy, and means including separate sources ofcarrier current connected in cir-'- cuit with the photoelectric sourcesin each of said pairs for simultaneously modulating a correspondingplurality of carrier currents respectively by the energy from a pair ofsaid sources in push-pull relation, each said carrier current being ofdifierent frequency and supplied to the respective sources of signalenergy in opposite phase.

4. In a television system, a push-pull modulation circuit comprising aplurality of pairs of separate photoelectric elements, each element of apair being subject to light rays of the same intensities, and meansconnected separately in circuit with the photoelectric elements in eachof said pairs for simultaneously supplying a corresponding plurality ofcarrier currents respectively to said pairs of elements in push-pullrelation, each said carrier current being of different frequency andmodulated by the energy in the respective pair of photoelectricelements.

5. In a television system, a plurality of sources of carrier currents ofdifierent frequencies, a separate corresponding plurality of multiplephotoelectric units each connected with one of said sources of carriercurrent, each of said multiple units comprising a plurality of lightsensitive elements subject to rays of the same light intensity andoperative in push-pull relation with the carrier current from therespective source for modulating the said carrier current.

6. In a television system, a push-pull modulation circuit comprising asource of carrier current having dual output circuits, a pair of loadresistors connected in series with said dual output circuits betweenterminals of opposite polarity, the junction of said resistorsconstituting a neutral point in said source of carrier current; a pairof photoelectric devices having anode and light sensitive cathodeelements subject to rays of the same intensities, a source of potentialconnected with said anode elements in common and With said neutral pointin said source of carrier current, separate connectionsfrom said cathodeelements to the remaining terminals of opposite polarity in said dualoutput circuits; and pushpull output connections from said neutral pointand each of said load resistors.

'7. In a television system, in combination, linear scanning apparatusfor simultaneously deriving a plurality of dual signals comprising duallight sensitive means having a plurality of pairs of photoelectricelements arranged in parallel linear relation, means for receivingsignal light rays equally on paired elements of said dual means, meansfor relatively moving said dual means in scanning relation to an objectwhereby signal light rays from various lines in said object are receivedby said dual light sensitive means and means connected separately in circuit with the photoelectric elements in each of said pairs forsimultaneously supplying a corresponding plurality of carrier currentsrespectively to said pairs of elements in push-pull relation, each saidcarrier current being of different frequency and modulated by'the energyin the respective pair of photoelectric elements.

8. In a television system, scanning apparatus for deriving dual signalscomprising a photoelectric device containing dual light sensitive meansso constructed and arranged as to receive signal light rays from onedirection only equally on each element of said dual means, means formoving said device in scanning relation with respect to an object,signal light rays being directed to said device from said object invarying directions, and means cooperative with the aforesaid means fororienting said device to the direction of the signal light rays fromthevarious points scanned in the object so that substantially equal lightintensity is received at each element of said dual light sensitivemeans.

9. In a television system, in combination, photoelectric means havingdual light sensitive cathode connections and single anode connections,scanning means for, directing signal light rays from an object to betelevised simultaneously on said photoelectric means, dual signals beingemanated at said dual cathode connections with respect to said singleanode connection in accordance with the light intensity in a particularportion of said object, and meansconnected separately in circuit withsaid photoelectric means between said dual cathode connections and saidsingle anode connection for supplying a carrier current in push-pullrelation to said photoelectric means for modulation thereby.

10. In a television system, in combination, scanning apparatus forderiving dual signalsineluding a single photoelectric device having duallight sensitive means, a pivotally mounted base member for supportingsaid device, a roller mounted in a projecting portion of said basemember, a cam surf-ace, spring means connected with said pivotallymounted base member and adapted to maintain. said roller in contact withsaid cam surface, and means for moving said base member with respect tosaid cam in a scanning motion, said spring means maintaining said rollerin cooperation with said cam for orienting said photoelectric device toreceive light rays from varying directions equally on said dual lightsensitive means.

11. In a television system, in combination, scanning apparatus forderiving dual signals including a single photoelectric device havingdual light sensitive means, a pivotally mounted base member forsupporting said device, a cam runner, a pilot member slidably connectedwith said base member andhaving roller means engaged with said camrunner for orienting said photoelectric device to receive light raysfrom varying directions equally on said dual light sensitive means, andmeans for moving said base member in a scanning motion, said pilotmember being moved therewith for operation with respect there- WALTERSOLLERQ

